Bromobenzene Transforms Lanthanoid Pseudo-Grignard Chemistry

Divalent lanthanoid pseudo-Grignard reagents PhLnBr (Ln= Sm, Eu and Yb) can be easily prepared by the oxidative addition of bromobenzene (PhBr) to lanthanoid metals in tetrahydrofuran (THF). PhLnBr reacts with bulky N,N'-bis(2,6-di-isopropylphenyl)formamidine (DippFormH) to generate Ln(II) complexes, namely [Ln(DippForm)Br(thf)(3] 2)center dot 6thf (1; Sm, 2; Eu), and [Yb(DippForm)Br(thf)(2)] (2) center dot 2thf (3; Yb). Samarium and europium (in 1 and 2) are seven coordinate, whereas ytterbium (in 3) is six coordinate, and all are bromine-bridged dimers. When PhLnBr reacts with 3,5diphenylpyrazole (Ph2pzH), both divalent (5; [Eu(Ph(2)pz)(2)(thf)4]) and trivalent (4a; [Sm(Ph(2)pz)(3)(thf)(3)]center dot 3thf, 4b; [Sm(Ph(2)pz)(3)(dme)(2)]center dot dme) complexes are obtained. In the monomeric compounds 4(a,b), samarium is nine coordinate but europium is eight coordinate in 5. The use of PhLnBr in this work transforms the outcomes from earlier reactions of PhLnI.

Automated summary

This study demonstrates the preparation of divalent lanthanoid pseudo-Grignard reagents PhLnBr (Ln= Sm, Eu and Yb) by the oxidative addition of bromobenzene (PhBr) to lanthanoid metals in tetrahydrofuran (THF). The reaction of PhLnBr with bulky N,N'-bis(2,6-di-isopropylphenyl)formamidine (DippFormH) generates Ln(II) complexes, and the reaction with 3,5-diphenylpyrazole (Ph2pzH) leads to the formation of both divalent and trivalent complexes. The use of PhLnBr in this work leads to different outcomes compared to previous reactions with PhLnI.